Numbers 8:16-18

16for they are 1exclusively given to Me from among the sons of Israel. I have taken them for Myself 2instead of the firstborn of every womb, the firstborn of all the sons of Israel.

17For 3every firstborn among the sons of Israel is Mine, among the people and among the animals; on the day that I fatally struck all the firstborn in the land of Egypt, I sanctified them for Myself.

18But I have taken the Levites instead of every firstborn among the sons of Israel.